6648991 has 2 divisors, whose sum is σ = 6648992. Its totient is φ = 6648990.

The previous prime is 6648979. The next prime is 6648997. The reversal of 6648991 is 1998466.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6648991 - 2¹⁵ = 6616223 is a prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6648997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3324495 + 3324496.

It is an arithmetic number, because the mean of its divisors is an integer number (3324496).

Almost surely, 2^6648991 is an apocalyptic number.

6648991 is a deficient number, since it is larger than the sum of its proper divisors (1).

6648991 is an equidigital number, since it uses as much as digits as its factorization.

6648991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 43.

The square root of 6648991 is about 2578.5637475153. The cubic root of 6648991 is about 188.0407241640.

The spelling of 6648991 in words is "six million, six hundred forty-eight thousand, nine hundred ninety-one".